The components that are used to generate and transfer electrical energy to end users are well known in the art. Electrical power producers generally generate electrical power at very high initial voltages. Handling of such high voltages requires substantial electrical insulation. The insulation requires control of heat that is generated from the transmission of the electrical energy and maintenance of its dielectric properties.
The primary purpose of the types of fluids needed for electrical transformers and fluid-filled transmission lines, hereinafter referred to as electrical insulating fluid, is to maintain cooling properties and fluid characteristics while in use within the system so as to maintain appropriate temperature as well as dielectric strength on demand. The heat of the transformer unit, for example, can increase to high levels for extended periods of time which the fluid must be able to tolerate without losing its properties. Additionally, the operation of transformers and the process of heat dissipation at various ambient temperatures subjects the fluid to constant stresses.
It has been found that certain fluids have high electrical insulating and heat dissipation properties. These fluids are used with such electrical components as transformers and fluid filled transmission lines. One particular problem, even with such fluids, is that over time and with substantial exposure to high voltage electricity, their beneficial characteristics, such as insulating and/or heat dissipation properties, degrade.
The industry uses a variety of insulating fluids which are easily available and cost effective. Examples are mineral oil, silicone fluid and synthetic hydrocarbon oils used in transformers, power cables and capacitors. Such fluids have certain properties that allow them to function satisfactorily. They must be electrically insulating and dissipate heat, and they must resist break-down. However, currently used fluids also have several deficiencies or concerns.
Many of the current fluids pose safety or contamination concerns. That is, they can be toxic to humans and animals. Many electrical components holding such fluids are situated near water or waterways where leakage or spills can cause serious damage to water and marine life. Leaks or spills on land can threaten ground water and contaminate soil.
Most of the current fluids are petroleum based and thus are derived from non-renewable starting materials. The amount of fluid of this type in use is significant. For example, one 15 MVA transformer (serving approximately 2000 customers, both residential and commercial) requires on the order of 3,600 gallons of electrically insulating fluid. One mile of fluid filled transmission cable (6 inch diameter) requires about 7,000 gallons. There are approximately 20,000 miles of high-pressure fluid filled transmission cables in the United States, most in larger cities and therefore near water or waterways.
Significant amounts of resources, both time and money, are spent by electrical power companies, in designing and implementing plans and systems to deter leaks or spills and to monitor transformers and transmission cables of these types for leaks or spills. It is estimated such costs are in the millions of dollars in the United States alone. Additionally, substantial resources are expended in reporting leaks or spills, even minor ones, because of environmental rules and regulations, at least with regard to petroleum based fluids. And, of course, the effect of leaks or spills can be very costly, as can remediation of the same.
Therefore, there have been attempts to look to new sources for such fluids. Such attempts need to address both the environmental concerns as well as the issue of renewability of source.
There are several fundamental properties that electrical insulation fluids require. These are:
1. High oxidation stability:                a. long life and protection;        b. no oxidation products;        c. no changes in chemical properties.        
2. Viscosity Characteristics:                a. low pour point for cold temperature service, particularly in cold temperature regions; and        b. high Viscosity Index for best viscosity under various operating temperatures.        
3. Corrosion Inhibition Properties:                a. inhibit contaminants in the fluid;        b. inhibit water;        c. inhibit oxidation by-products.        
4. Seal, Polymer, Resin Compatibility:                a. with old and new seal materials; and        b. with resin and other insulating materials.        
Another demand placed upon electrical insulation fluids is the requirement that they maintain a certain degree of stability in terms of insulating properties despite some of the physical and chemical changes that take place during extended use.
Therefore, it is a primary object of the present invention to provide electrical insulation fluids which improve over and/or solve at least a portion of the problems and deficiencies in the art.